What you carry at this position in your DNA and what research says about it.
Serotonin Receptor Function: 5/10 evidence, 60 publications.
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Sample genotype (not yours): G/G
Higher Joint Inflammation Risk but Better Medication Tolerability
Susceptibility to joint inflammation is slightly elevated, but there is a lower risk of metabolic side effects from certain medications. Serotonin signaling remains at a stable baseline.
What this genotype means: Elevated risk of rheumatoid arthritis; Lower risk of risperidone-induced weight gain; Typical emotional stress resilience.
Sample genotype (not yours): A/A
Higher Stress Sensitivity and Medication Side Effect Risk
Sensitivity to emotional stress, panic, and mood fluctuations is elevated. There is also a higher likelihood of experiencing side effects from common antidepressants.
What this genotype means: Increased sensitivity to stress and panic; Higher risk of antidepressant-induced sexual dysfunction; Typical risk of rheumatoid arthritis.
Sample genotype (not yours): G/A
Increased Joint Inflammation and Medication Side Effect Risk
Susceptibility to joint inflammation is slightly elevated, and there is a higher likelihood of experiencing metabolic side effects from certain medications. Emotional stress responses remain typical.
What this genotype means: Elevated risk of rheumatoid arthritis; Higher risk of risperidone-induced weight gain; Potentially reduced response to sertraline.
Gene function and biological role
Gene Function: The HTR2A gene encodes the 5-hydroxytryptamine receptor 2A, a major G-protein-coupled receptor for serotonin widely expressed throughout the central nervous system and peripheral tissues [1]. This receptor plays a fundamental role in modulating mood, anxiety, perception, and cognitive processes by regulating synaptic neurotransmission [2]. Beyond its neurological functions, the receptor is also expressed on platelets and immune cells, where it participates in inflammatory pathways and vascular responses [3]. Because of its diverse physiological roles, variations in this gene are heavily studied in relation to psychiatric conditions, personality traits, and autoimmune susceptibility [4].
Variant Impact: The rs6313 variant is a synonymous single nucleotide polymorphism located in exon 1 of the HTR2A gene, often referred to in scientific literature as the T102C or C102T polymorphism [1]. Although it does not alter the encoded serine amino acid at position 34, this genetic change is in tight linkage disequilibrium with regulatory variants that influence HTR2A promoter activity and gene expression levels [5]. The minor A allele (corresponding to the T allele in older literature) has been associated with altered receptor density and splice isoform expression in the human cortex [1]. Consequently, this variant serves as a key genetic marker for individual differences in serotonin signaling, emotional processing, and drug response [6].
Key Insight: A silent genetic change that does not alter any amino acids can still significantly impact receptor expression levels and drug sensitivity. The same serotonin receptor that regulates mood also influences immune cell activation in joint tissue.
Location: HTR2A. Chromosome 13 · 13q14.2 · 46.9 Mb
Estimated prevalence by population
Global 36.0%; European 34.8%; African 38.8%; East Asian 17.2%; South Asian 34.2%; Americas 37.2%; Ashkenazi 25.3%; Finnish 44.1%; Middle Eastern 22.4%; Amish 60.7%.
Estimated GG genotype frequency.
Global 47.6%; European 48.4%; African 47.0%; East Asian 48.5%; South Asian 48.6%; Americas 47.6%; Ashkenazi 50.0%; Finnish 44.6%; Middle Eastern 49.9%; Amish 34.4%.
Estimated GA genotype frequency.
Global 16.3%; European 16.8%; African 14.2%; East Asian 34.3%; South Asian 17.2%; Americas 15.2%; Ashkenazi 24.7%; Finnish 11.3%; Middle Eastern 27.8%; Amish 4.9%.
Estimated AA genotype frequency.
Showing effects for G/G genotype
Immunity & Inflammation
Autoimmune Diseases
Rheumatoid Arthritis. Evidence: 3/10. Source: PMID 18006541. Increased Risk.
Neurology & Mental Health
Anxiety & Stress Disorders
Stress and Panic. Evidence: 3/10. Source: PMID 21930285. Typical.
Pharmacogenomics
Antidepressant & Psychiatric Drug Response
Antipsychotic Weight Gain. Evidence: 5/10. Source: PMID 16633140. Lower Risk.
Antidepressant Response. Evidence: 5/10. Source: PMID 31792367. Typical.
Showing effects for A/A genotype
Rheumatoid Arthritis. Evidence: 3/10. Source: PMID 18006541. Typical Risk.
Stress and Panic. Evidence: 3/10. Source: PMID 21930285. Higher Sensitivity.
Antipsychotic Weight Gain. Evidence: 5/10. Source: PMID 16633140. Higher Risk.
Antidepressant Response. Evidence: 5/10. Source: PMID 31792367. Higher Side Effects.
Showing effects for G/A genotype
What this genotype means for the people who carry it
Sample genotype: GG (Homozygous)
Autoimmune pathways show a higher baseline of activation, which has been linked to an increased susceptibility to rheumatoid arthritis in European populations [1]. This genetic profile is associated with higher expression of the HTR2A receptor, which can influence peripheral immune responses and joint tissue inflammation [1]. However, in psychiatric contexts, this baseline receptor density is associated with a lower risk of metabolic side effects [2]. Specifically, clinical studies indicate a significantly reduced risk of experiencing severe weight gain when treated with atypical antipsychotics like risperidone [3]. Standard antidepressant therapies also tend to be well-tolerated, with a lower incidence of common side effects compared to other genotypes [4].
Elevated risk of rheumatoid arthritis; Lower risk of risperidone-induced weight gain; Typical emotional stress resilience.
Sample genotype: AA (Homozygous)
Serotonin receptor density in the prefrontal cortex is altered, which can influence emotional reactivity and stress resilience [1]. This genetic profile is frequently associated with a higher susceptibility to panic symptoms, anxiety, and seasonal mood changes [2]. In clinical settings, these receptor differences translate to a distinct medication response profile [3]. Individuals with this genotype are more prone to specific side effects, such as citalopram-induced sexual dysfunction [3]. There is also an increased risk of metabolic side effects, including significant weight gain, during treatment with atypical antipsychotics like risperidone [4]. Conversely, there is a lower risk of joint inflammation, as this genotype is not associated with the elevated rheumatoid arthritis risk seen in G allele carriers [5].
Increased sensitivity to stress and panic; Higher risk of antidepressant-induced sexual dysfunction; Typical risk of rheumatoid arthritis.
Sample genotype: GA (Heterozygous)
Susceptibility to autoimmune joint issues is slightly elevated due to the presence of the G allele, which is associated with higher inflammatory signaling in joint tissues [1]. This genetic pattern can lead to increased production of inflammatory cytokines like TNF-alpha and IL-6 in response to immune triggers [1]. On the pharmacogenomic front, carrying one copy of the A allele alters how the body responds to psychiatric medications [2]. Clinical trials show an increased risk of experiencing significant weight gain when taking antipsychotic medications such as risperidone [3]. Additionally, certain selective serotonin reuptake inhibitors, like sertraline, may be less effective [4].
Elevated risk of rheumatoid arthritis; Higher risk of risperidone-induced weight gain; Potentially reduced response to sertraline.
Variants with shared genetic architecture
rs6311 · HTR2A Gene · Chr 13 · Antidepressant Side Effects
rs6314 · HTR2A Gene · Chr 13 · Episodic Memory
rs7997012 · HTR2A Gene · Chr 13 · Antidepressant Response
Variations in 5-HT2A influence spatial cognitive abilities and working memory.
Temperament profiles, 5-HT2A genotype, and response to treatment with SSRIs in major depression.
Risperidone-related weight gain: genetic and nongenetic predictors.
Content updated August 2026.
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